Solid surface cover materials used in flooring include rigid surfaces such as wood, metal, marble, or ceramic tile, and resilient surfaces such as vinyl or rubber. They are simple to keep clean and have less of a problem harboring bacterial growth than do textile products. However solid surface cover materials lack the softness, the cushion, and the textile quality of carpets.
Flooring products, such as tufted, flocked, knit or woven pile carpets, provide abrasion resistance as well as cushion with a soft textile feel by anchoring fibers into a backing and holding them upright, as in a pile carpet. Compared to solid surfaces these textile upright-oriented products are less durable, tend to collect dust and dirt, provide spaces for bacterial growth in the interstices between the pile fibers, and they are difficult to clean and sanitize. They also consume excessive quantities of fiber to form the pile. Pile structures should also be secured on the floor, either by attaching with heavy adhesives, or by stretching across the floor to avoid warping, bulging, or seam-separation, as they expand and contract with changes in temperature and humidity. Pile structures used as modular “tiles” should be substantially reinforced under the pile with materials insensitive to temperature and humidity variations, such as glass.
Hybrid structures, with partially fibrous and partially solid faces, such as those disclosed by Petry et al. U.S. Pat. No. 3,493,018, have also been developed. These reduce but do not eliminate the limitations of solid or fibrous pile structures.
Many attempts have been made to adapt textile fabrics to flooring use. One tactic has been to assemble a basically flat textile fabric over a sublayer of adhesive backed with various layers of sub-surface reinforcement using materials such as glass. Such sub-surface reinforcement dimensionally stabilizes the face fabric, and it diminishes or eliminates warping caused by the expansion and contraction of fabric and adhesive, resulting from temperature and humidity variations during use on the floor. WO 1999/019557 utilizes a woven face fabric backed by reinforcing layers. Vinod U.S. Pat. No. 5,965,232 discloses a decorative fabric attached to dimensionally-stabilizing subsurface layers and cushioning layers, and further face-stabilization using surface finishes. Further improvements are offered by WO 2002/102582 and U.S. Pat. No. 7,064,092, which disclose pre-stabilized face fabrics and special sub-facial reinforcements.
All flat prior-art fabric/backing laminates, with or without sub-surface reinforcements, create a relatively stiff upper fabric/adhesive layer, which lacks the cushioning characteristics of textile floor coverings, even when backed by soft and resilient backings. Furthermore, such flat laminates are subject to delamination and fraying at the cut edges when subjected to heavy flooring traffic, unless the face fabric is impregnated with adhesives at least along the edges. However, such impregnation further deteriorates the textile feel and face-cushion quality of the laminate.
To a certain extent, U.S. patent application Ser. Nos. 10/611,470 and 10/307,186, which are incorporated herein by reference in their entireties, describe a floorcovering with a textile surface and the characteristics of a soft floor, without the problems of dirt and dust accumulation and the use of heavy reinforcements. Such floor coverings can be used either as a modular “tile” or a “broadloom” carpet extending across entire floors. The '470 and '186 applications disclose a composite of a highly-conformable fibrous outer layer, a continuous adhesive layer, and a backing layer that are simultaneously laminated and/or embossed with heat and pressure applied against the fibrous outer layer. The embossing/laminating tool has tall protrusions, which form depressed areas on the surface that are surrounded by elevated areas. Within the depressed areas, the fibrous outer layer, the adhesive layer, and the backing layer are highly densified thereby “anchoring” the fabric at intervals by adhesive bonding. Solid thermoplastic adhesives or “viscous/paste-like” thermosets are utilized, thereby preventing the adhesive from propagating to the upper surface within the elevated areas and preserving textile and tactile aesthetics. Consequently, at the elevated areas, inter-bonding of the fibrous outer layer and backing layer is minimal or absent and, as a result, the combined density of the outer layer, adhesive layer, and backing layer is lower in the elevated areas than the depressed areas. In other words, there is a topographical variation in density between the elevated areas and the depressed areas. It was, also however noted that, due to the absence of substantial interbonding within the elevated areas, the fibrous outer layer and backing layer may separate. By contrast, within the depressed areas, wherein the fabric is “anchored” by bonding, the layers cannot be separated without damage to the fibrous outer layer. The undulated three-dimensional fabric/adhesive face structure of these composites, with intermittent bonding to the backing at intervals, allows them to absorb lateral stresses by contracting or expanding the arched spans or “loops” of the face layer connecting the bonded depressed areas, in a manner analogous to the “flexing” of a spring. This characteristic avoids warping on the floor, and allows the construction of floor coverings without the need for heavy sub-surface reinforcement that result in facial stiffness.
The need to reach and anchor the face layer intermittently and exclusively at the depressed areas also limits product aesthetics and performance for the floorcovering of the '470 and '186 applications. Within the elevated areas, the unattached or lightly-attached face fabric may deform and rise slightly at cut edges when subjected to heavy traffic for long periods of time, creating subtle but visible seam lines. The elevated areas may also slightly flatten with severe traffic. Furthermore the simultaneous lamination and embossing process needs to be performed using tools with tall protrusions allowing clearances between the recessions of the heated tool and the face fabric, and limiting design capabilities. The need remains for a more durable floorcovering that takes advantage of the product structuring concepts disclosed by the '470 and '186 applications, without these limitations.